JP4447099B2 - Alkaline zinc and zinc alloy plating bath - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plating bath for electrodepositing shiny zinc or zinc alloy on various substrates, a brightener for use in the plating bath, and a plating method using the plating bath.
[Prior art]
While environmental measures in recent years have been screamed, the mainstay of zinc plating has shifted from plating baths using sodium blue soda to zincate baths using caustic soda that can be easily discharged, and technological development related to this has also progressed. is doing. In the zincate bath, the properties of the plating film depend greatly on the brightener, so the uniformity of the plating film has not been improved with the existing brightener. As a method for solving this problem, JP-A-8-209379 and JP-A-11-193486 propose a plating bath containing a reaction product of dialkylaminopropylamine, urea and dichloroalkyl ether as a main luster component. However, in the plating bath using the reaction product, although the throwing power is improved as compared with the case of using the conventional galvanizing brightener, the product to be plated that requires more accuracy, for example, the shape The complicated press product and cylindrical product still have a large difference in film thickness due to current density, and it was difficult to obtain a uniform film thickness. Therefore, the actual situation is that a film having a uniform film thickness is usually obtained by using an auxiliary anode.
[0002]
[Problems to be solved by the invention]
It is an object of the present invention to provide an alkaline zinc and zinc alloy plating bath that has good film physical properties even when the current density changes and can obtain a uniform plating film thickness.
It is an object of the present invention to provide a brightener for alkaline zinc and zinc alloy plating baths that has good film physical properties even when the current density changes and can provide a uniform plating film thickness.
Another object of the present invention is to provide an efficient plating method using the above plating bath.
[0003]
[Means for Solving the Problems]
The present invention relates to a reactive product obtained by reacting (a) urea or thiourea, (b) dialkylaminoalkylamine and (c) dichloroalkyl ether with (d) epihalohydrin for alkaline zinc and zinc alloy plating baths. It was made based on the knowledge that the above problem can be solved efficiently when used as a brightener.
That is, the present invention contains (a) urea or thiourea, (b) dialkylaminoalkylamine and (c) a water-soluble reactive product of dichloroalkyl ether and (d) epihalohydrin. An alkaline zinc and zinc alloy plating bath is provided.
The present invention also provides a brightener for alkaline zinc and zinc alloy plating baths characterized by containing the reactive product.
The present invention also provides an alkaline zinc and zinc alloy plating method using the alkaline zinc and zinc alloy plating bath.
[0004]
DETAILED DESCRIPTION OF THE INVENTION
The reactive product obtained by reacting (a) urea or thiourea, (b) dialkylaminoalkylamine and (c) dichloroalkyl ether with (d) epihalohydrin used as a brightener in the present invention is, for example, It can obtain by the method shown in.
(A) 2 mol of dialkylaminoalkylamine, (c) 0.1-1 mol of dichloroalkyl ether and (d) 0.1-1 mol of epihalohydrin, The total amount of c) and (d) is preferably 0.5 to 1 mol, more preferably 1 mol, and the reaction is carried out at a temperature of 90 to 170 ° C. for 1 to 10 hours so as to obtain a water-soluble reaction product. . The obtained reaction product preferably has a molecular weight of about 3000 to 100,000, more preferably about 10,000 to 50,000.
(B) As dialkylaminoalkylamine, it is preferable that carbon number of each alkyl group is 1-6, More preferably, it is 1-3. Specifically, dimethylaminoethylamine, diethylaminoethylamine, dipropylaminoethylamine, dibutylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, or a mixture of two or more of dibutylaminopropylamine preferable.
[0005]
(C) As dichloroalkyl ether, it is preferable that carbon number of an alkyl group is 1-6, More preferably, it is 1-3. Specifically, one kind or a mixture of two or more kinds of dichloroethyl ether, dichloropropyl ether, dichlorobutyl ether are preferable.
(D) As the epihalohydrin, epichlorohydrin, epibromohydrin, or a mixture of two or more of ethylene chlorohydrin is preferable.
The reaction product is preferably obtained by reacting (a) and (b) and then reacting (c) and (d), but (a) to (b) can be reacted at the same time.
In this invention, it is preferable to contain 0.1-50 g / L of the said water-soluble reaction product in a plating bath, More preferably, it is 0.5-20 g / L.
The alkaline zinc and zinc alloy plating bath of the present invention preferably contains 1 to 30 g / L in a dissolved zinc form, more preferably 5 to 20 g / L. It is preferable to contain 60-200 g / L of alkali metal hydroxide, for example, sodium hydroxide, more preferably 90-150 g / L.
[0006]
The alkaline zinc and zinc alloy plating bath of the present invention preferably has a pH of 13 or more, more preferably PH14 or more.
Various additives can be contained in the alkaline zinc and zinc alloy plating bath of the present invention.
For example, it is preferable to contain 1-100 g / L of alkali silicates such as colloidal silica and No. 3 silicon as silicate, and more preferably 5-50 g / L.
In the present invention, examples of the zinc alloy include alloys of zinc and one or more metals such as iron, nickel, cobalt, and manganese. The amount of these metals is preferably about 0.1 to 60% by mass. When obtaining these alloy platings, it is preferable to change the metal ion concentration in the plating bath depending on the type of alloy to be obtained and the alloy ratio thereof. For example, for zinc 5 to 20 g / L, iron It is good to add 1 type, or 2 or more types, such as 30-1000 mg / L, nickel 0.02-5 g / L, cobalt 0.02-5 g / L, manganese 0.02-40 g / L. Metal ions are preferably supplied in the form of chlorides or sulfates.
[0007]
A chelating agent is preferably used to dissolve the metal salt. Examples of chelating agents include hydroxycarboxylic acids such as citric acid, tartaric acid, gluconic acid and glycolic acid and salts thereof, amino alcohols such as monoethanolamine, diethanolamine and triethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylene. Reactions of polyamines such as pentamine, polyimines, polyamines and epihalohydrins (ethylene chlorohydrin, epichlorohydrin, epibromohydrin) or halogen ethers (dichloroethyl ether, dichloropropyl ether, dichlorobutyl ether) It is preferable to use it. These can be used alone or in combination. These are preferably contained in the bath in an amount of 0.1 to 100 g / L, more preferably 1 to 50 g / L.
[0008]
In the present invention, only the above-mentioned water-soluble reactant can be used as a brightener, but an auxiliary gloss component can also be added. Examples thereof include aldehydes such as vanillin, benzaldehyde, hydroxybenzaldehyde, ethyl vanillin, veratraldehyde, anisaldehyde, and a reaction product of nicotinic acid with halogenated hydrocarbon, alkylene oxide, epihalohydrin, halogen ether, and the like.
In the present invention, a substrate to be plated (iron, copper, brass or the like) is used as a cathode, a zinc plate or nickel or the like is used as an anode, and the plating bath is used, for example, a current density of 0.01 to 20 A / dm ² , a temperature. A plating method including a step of plating usually for 5 to 80 minutes (for example, a plating film thickness of 3 to 20 μm) until a predetermined plating thickness is obtained at 15 to 50 ° C. is also provided.
【The invention's effect】
According to the present invention, a zinc and zinc alloy plating film excellent in uniformity and film physical properties can be obtained as compared with brighteners used in conventional alkaline zinc and zinc alloy plating baths.
Next, the present invention will be described using examples.
[0009]
【Example】
Example 1
1 mol of urea, 2 mol of dimethylaminopropylamine, 0.5 mol of dichloroethyl ether and 0.5 mol of epichlorohydrin are reacted at a temperature of 140 ° C. for 5 hours to produce a water-soluble reaction having a molecular weight of about 30,000. A product was obtained (brightener A).
This brightener A contains 0.5 g / L, Zn 10 g / L, and NaOH 120 g / L, and the balance is water. The plating bath (PH14 or more), the iron plate as the cathode, the zinc plate as the anode, A Hull Cell test was performed at 2A and a temperature of 25 ° C. for 20 minutes. As a result, a galvanized film having a uniform film thickness superior to conventional brighteners from a high current density part to a low current density part was obtained.
Example 2
1 mol of urea, 2 mol of dimethylaminopropylamine, 0.5 mol of dichloroethyl ether and 0.5 mol of epibromohydrin are reacted at a temperature of 140 ° C. for 5 hours to produce a water-soluble reaction having a molecular weight of about 35,000. A product was obtained (brightener B).
In a plating bath (PH14 or more) containing 0.5 g / L of this brightener B, 10 g / L of Zn, 120 g / L of NaOH, 0.005 g / L of 1-propyl-pyridinium 3-carboxylate, and the balance being water The hull cell test was performed for 20 minutes at a total current of 2 A and a temperature of 25 ° C. using an iron plate as a cathode and a zinc plate as an anode. As a result, a galvanized film having a uniform film thickness superior to conventional brighteners from a high current density part to a low current density part was obtained.
[0010]
Example 3
1 mol of urea, 2 mol of dimethylaminoethylamine, 0.5 mol of dichloropropyl ether and 0.5 mol of ethylene chlorohydrin are reacted at a temperature of 140 ° C. for 5 hours to produce a water-soluble reaction product having a molecular weight of about 30,000. (Brightener C) was obtained.
This brightener C contains 2 g / L, Zn 10 g / L, NaOH 120 g / L, and the balance is water. The plating bath (PH14 or more), the iron plate as the cathode, the zinc plate as the anode, and the total current amount 2A The hull cell test was performed at a temperature of 25 ° C. for 20 minutes. As a result, a galvanized film having a thicker film thickness than that of the conventional brightener was obtained from the high current density part to the low current density part.
Example 4
1 mol of urea, 2 mol of diethylaminopropylamine, 0.5 mol of dichloroethyl ether and 0.5 mol of propylene chlorohydrin are reacted at a temperature of 140 ° C. for 5 hours to produce a water-soluble reaction product having a molecular weight of about 30,000. (Brightener D) was obtained. In a plating bath (PH14 or more) containing 4 g / L of this brightener D, 10 g / L of Zn, 150 g / L of NaOH, 0.5 g / L of 1-ethanol-pyridinium 3-carboxylate, and the balance being water, A hull cell test was performed for 20 minutes at a total current of 2 A and a temperature of 25 ° C. using an iron plate as a cathode and a zinc plate as an anode. As a result, a galvanized film excellent in gloss with a uniform film thickness from a conventional brightener from a high current density part to a low current density part was obtained.
Example 5
1 mol of urea, 2 mol of diethylaminopropylamine, 0.7 mol of dichloroethyl ether, and 0.3 mol of epibromohydrin are reacted at a temperature of 140 ° C. for 5 hours to produce a water-soluble reaction product having a molecular weight of about 35,000. (Brightener E).
This brightener E was 4 g / L, Zn 10 g / L, NaOH 150 g / L, Ni 1.5 g / L, a reaction product of alkylamine and epihalohydrin 20 g / L, 1-ethanol-pyridinium 3-carboxylate 0.5 g / L L, No. 3 silicon 30g / L, the remainder is water plating bath (PH14 or more), iron plate as cathode, zinc plate as anode, Hull cell test at total current 2A, temperature 25 ° C for 20 minutes I did it. As a result, a galvanized film excellent in gloss with a uniform film thickness from a conventional brightener from a high current density part to a low current density part was obtained.
Comparative Example 1
As a plating bath using a conventional brightener, Zn 10 g / L, NaOH 150 g / L, a reaction product of imidazole and epichlorohydrin 0.5 g / L, a reaction product of dimethylamine and epichlorohydrin 1 g The plating solution contained was an iron plate as a cathode and a zinc plate as an anode, and a hull cell test was performed at a total current amount of 2 A and a temperature of 25 ° C. for 20 minutes. As a result, the high current density part had a thick plating film thickness, but the low current density part had an extremely thin zinc plating film.
Comparative Example 2
As a plating bath using a conventional brightener, Zn 10 g / L, NaOH 150 g / L, Ni 1.5 g / L, reaction product of diethylenetriamine and epichlorohydrin 20 g / L, reaction of imidazole and epichlorohydrin A plating solution containing 0.5 g / L of a product and 1 g of a reaction product of dimethylamine and epichlorohydrin, an iron plate as a cathode, a zinc plate as an anode, a total current amount of 2 A, and a temperature of 25 ° C. for 20 minutes. Was done. As a result, the high current density part was thicker than that of Example 5, and the low current density part was obtained as a galvanized film having an extremely thin film thickness as compared with Example 5.
The results are summarized in Table 1.
[Table 1]
Table 1 Relationship between distance (cm) and film thickness (μm) from high current portion of Hull cell test panel 1 3 5 7 9
Example 1 7.4 6.9 6.4 6.1 5.6 μm
Example 2 6.3 6.1 5.8 5.4 4.8
Example 3 5.4 5.1 4.7 4.2 3.7
Example 4 5.6 5.4 5.2 4.9 4.5
Example 5 8.3 7.6 6.3 5.5 4.7
Comparative Example 1 15.7 10.4 7.9 3.9 1.4
Comparative Example 2 14.2 9.6 6.3 3.5 1.7

Claims (7)

(A) For 1 mole of urea , (b) 2 moles of dialkylaminoalkylamine, (c) 0.1-1 mole of dichloroalkyl ether and (d) 0.1-1 mole of epihalohydrin An alkaline zinc and zinc alloy plating bath characterized by containing a product.   The plating bath according to claim 1, comprising 0.1 to 50 g / L of a water-soluble reactant.   The plating bath of Claim 1 or 2 containing 1-30 g / L of zinc and 60-200 g / L of alkali hydroxide.   The plating bath according to any one of claims 1 to 3, comprising 1 to 100 g / L of colloidal silica or alkali silicate.   Any one of Claims 1-4 which contains 1 or more types of iron 30-1000 mg / L, nickel 0.02-5 g / L, cobalt 0.02-5 g / L, manganese 0.02-40 g / L as a metal ion. The plating bath according to claim 1.   A method for plating zinc or a zinc alloy, wherein the plating bath according to any one of claims 1 to 5 is used. (A) For 1 mol of urea , (b) 2 mol of dialkylaminoalkylamine, (c) 0.1 to 1 mol of dichloroalkyl ether and (d) 0.1 to 1 mol of epihalohydrin are produced as a water-soluble reaction. Brightener for alkaline zinc and zinc alloy plating bath characterized by containing a product.